Process of preparing amino alcohols



Patented June 13, I933 UNITED STATES PATENT OFFICE" FRIEDRICH s'roLz, KARL Bo'r'rcnER, AND JULIUS Hennnnsnnnnnon rnnnxron'r- ON-THE-MAIN-HOCHST, AND WALTER KROHS, on BAID-SODEN, GERMANY, nssIGNoBs, BY ivrnslvn ASSIGNMENTS, TO wINTHRoP CHEMICAL COMPANY, Inc, on NEW YORK,

Y., A CORPORATION OF N EW YORK' rnocnss on PREP RING Amino A oonoLs N. Drawing. Application ma. Mar a, 1328, Serial No. 314,537, and in, Germany October 29, 1927.

The present invention relates to a process of preparing amino alcohols.

The preparation of aromatic amino alcohols reducing aromatic amino ketones is connected with difficulties.

Now we have found thatthe said amino alcohols can be obtained in a technically simple manner by starting from basic ketones in which at least one hydrogen atom of the amino-group is substituted by the benzyl radicle or another aralkyl radical.

If, for instance, a benzylalkylamino ketone is hydrogenated with hydrogen in the pres ence of a metal-catalyst of the platlnumgroup, there is not only reduced thGCOi-gTOHP to GHOI-I but there is also spht off the benzyl radicle as toluene and in its place hydrogen introduced, a fact which could not be foreseen according to what has hitherto been disclosed on the subject. The reaction may be wherein R stands for an aromatic radical and R stands for hydrogen or an aliphatlc or an aralkyl radical. wvhenustarting from a dibenzylaminoketone there is obtained by the hydrogenation a primary amine.

The hydrogenation of the basic ketones aralkylated at the nitrogen may also be effectedwith theaid of a metal of the :lI'OIl-r group as catalyst and it proceeds rapidlyand smoothly when it is carried out under pressure and at anelevated temperature. Among the metals of the iron-group nickel is especially suitable as a catalyst; it can be replaced wholly or partly by another metal of the ironmost favorable temperature being one of about 100 C.

The amino alcoholsprepared in the abovedescribed manner and which are intended. to

beused for therapeutical purposes, are distinguished by their great purity.

Emam pl es c (1.) Preparation of 1-. 3C4 dihydroxyphenyl) 9 (N-methylbenzylamino) ethanone-l of the following formula:

and reduction thereof to L (3A -dihydroXyphenyl)-2-methylamino-2-ethanol l of the following formula:

186.5 grams of 1-(3. l-dihydroxyphenyl) -2- chloro-ethanone-l of the following formula:

no-O-co-omm a v I l f are dissolved in about four times its volume of alcohol and 242 grams of methyl-benzylamine are added drop by drop while stirring.

. The solution becomes slightly heated and assumes a darker coloration. After it has stood for about one day, it is precipitated with much water, freed from the microcrystalline precipitate by filtering with suction and washed with water and ether. The crude product can be purified by dissolving itin dilute hydrochloric acid and precipitating it carefully with ammonia. Itis then a faintly colored microcrystalline powder, which is scarcelysoluble in water and ether, fairly readily soluble in alcoholand melts at about 1209 C. while assuminga browncoloration. The hydrochloricacid solution assumes an intensive green coloration onaddition of iron chloride.

i 27.1 grams of the 1- (3.4c-dihydroxyphenyl) following formula CH2. CaHg chloric acid and some Water and after the addition of an aqueous solution of palladious i chloride and gum arabic the whole mixture is agitated with hydrogenat ordinarytemperature and under an excess pressure of about one atmosphere, until the theoretical quantity (2 mol) is taken up. The reaction liquor is then distilled with steam whereby the toluene produced passes over. Then the contents of the flask is freed from palladium by filtering it by suction and the aqueous solution is carefully precipitated with ammonia. After filtering by suction, the precipitate is washed with water, alcohol and ether. The microcrystalline precipitate can be purified by dissolving it in an acid and precipitating it with ammonia and then shows the properties of the racemic suprarenin base. The final prodnot unlike the starting material is difficultly soluble in alcohol and melts with decomposi tion at about 212 C. It has the following formula:

CHa

and reduction thereof to 1-phenyl-2-methylamino-propanol-l of the following formula:

CoHs-OHOH-CEP-OH:

242 grams of methylbenzylamine are introduced drop by drop into 218 grams of 1- phenyl-2-bromopropanone-1 of the following formula:

CH5GOOHCH3 dissolved in about 4 times its volume of alcohol. The temperature rises slightly and the liquid assumes a somewhat darker coloration. After standing for about one day, it is precipitated with ether, the hydrobromide of methylbenzylamine is removed by filtering with suction and the filtrate is freed from alcohol and ether by distillation. The residue is taken up with ether and agitated with water. The ethereal solution is dried by means of caustic potash, the ether distilled off and the residue distilled in Vacuo. The 1- phenyl -2 (N methyl -benzylamino) propanone-1 of the following formula:

ooH5-oocH-o1a3 N\ oHaCa s a pressure of 14 mm and a temperature of about 197-198 (3.; it crystallizes readily.

The reduction of the 1-phenyl-2-(N- methyl-benzylamino)-propanone-1 is performed as indicated in Example 1. After the toluene has been expelled with steam, the contents of the flask is freed from the palladium by filtration, the remaining liquor is rendered alkaline with caustic soda solution and extracted with ether. After drying and distilling off, there remains 1-phenyl-2- methylamino-propanol-l with the known properties. The free base melts at 7 8 (1., the oxalate at 254 C. It has the following formula:

osmo nononona (3) l phenyl-2- (N-methyl-benzylamino) propanone-l of the following formula:

C H GOCHOHs CH3 N CH2 OdH5 obtained from methyl'benzylamine and 1- phenyl-2-bromopropanone-1 of the following formula:

is' reduced in an alcoholic or diluted alcoholic solution with palladium black and hydrogen.

' After reduction has taken place, the catalyst is separated, the filtrate is acidified, the alcohol distilled off, and the residue dissolved in water. The 1-phenyl-2--methylamino-propanol-l of the following formula:

is precipitated from the aqueous solution by means of an alkali and taken up with ether.

acid. The oxalate inelts at a temperature of perature of 78 Cl, whereas the hydrochloride 254 (1, whereas the alcohol base obtained fronJ the oxalatemelts at a temperature of 78 i a 1..

(4;) 25 grams of the hydrochloride of 1- phenyl-2- (N-methylbenzylamino) -ethanone- 1 of the following formula: JBQ

o,m-.-oo -oH2- N V I GET-(RH; obtained by causing methylbenzylamine to i act upon l-phenyl-Q-bromo-ethanone 1 of the in a benzene solution, are dissolved in 200 cc. of water and, after the addition of a nickelcatalyst, hydrogenated in an autoclave at a temperature of about 90 C. under a pressure of 50 atmospheres, while using hydrogen.

The catalystis then filtered by suction, the

i eliminated toluene is isolated and the solution of the hydrochloride of 1-phenyl-2- obtained by causing methylbenzylamine to act upon 1-phenyl 2-bromopropanone-1 of the L following formula is dissolved in QN-hydrochloric acid and,

after the addition of the nickel-catalyst, hydrogenated for about one hour at a temperature of between 90 C. and 100 C. and under a pressure of atmospheres, while using hydrogen. The solution, after being separated from the catalyst and the formed toluene, is supersaturated with an alkali and the 1-phenyl 2-methylamino-propanol-l of the following formula:

is extracted with ether. The base melts after re-crystallization from cyclohexane at a temmelts at 189 C. a

(6) By causing methylbenzylamine to act upon 1- l-hydroxyphenyl) -2-chloro-ethanone-1 of the following formula:

in an alcoholic solution the 1- (4-hydroxyphenyl) 2 (N- methylbenzylamino) ethanone-l of the following formula:

is obtained which crystallizesfrom alcohol in lamellae. Its hydrochloride forms colorless crystals of the melting point 222 C.-224 C., which. are easily soluble in water and alcohol, more difliculty in acetone.

29.15 parts of the hydrochoride of 1-(4- hydroxyphenyl) -2- (N-methyl-benzylamino) ethanone-l are dissolved in 200 partsof water and, after the addition of a nickel-catalyst,

hydrogenated for about one hour at a tem- HOOHOH-CH;N/

is precipitated from the filtrate by means of potassium carbonate. It forms a white crystalline powder which is difficulty soluble in water and alcohol and which melts at a temperature between 183 C. and 184 C. The hydrochloride is readily soluble in water and melts at a temperature of between 152 C. and 153 C.- v a (7 l-phenyl-Q (N-methyl-benzylamino) propanone-l of the following formula:

CuH. CO-OHCH3 CH3 N/' L CHrcaHg obtainedby causing methylbenzylamine to is dissolved in alcohol or diluted alcohol and hydrogenated for about one hour in the presence of a nickel-catalystlat a temperature of between 80 C. and 90 C. and under a pressure of about 40 atmospheres while using hydrogen. The alcoholic solution, after being separated from the catalyst, is acidified, the alcohol is filtered off by suction and the salt is taken up with water. To separate the resulting 1phenyl-2-methylamino-propanol- 1 of the following formula:

the aqueous solution is mixed with an alkali and then extracted with ether. After having distilled the ether, a base is left-which, after re-crystallization from cyclohexane, melts at a temperature of between 77 C. and 78 C.

In the following claims the term catalyst of the iron group comprises iron, nickel and cobalt catalysts themselves or in mixture.

Vi e claim: 1. The new process of preparing amino alcohols, which consists in treating a ketone of the general formula wherein R- stands for a phenyl radical which may be mono-( l) or di"(3-4:) substituted by hydroxy and X stands for hydrogen "or methyl with hydrogen in the presence of a catalyst of the group consisting of palladium and nickel catalysts.

3. The new process of preparing aminoalcohols which consists in treating a ketone of the general formula:

X ncodn cntotm wherein R stands for a phenyl radical which may be mono-(3) or di-(3Ac) substituted by hydroXy, X stands for hydrogen or methyl, with hydrogen in the presence of a palladium catalyst.

4. The new process of preparing aminoalcohols which consists in treating a ketone of the general formula X. R.C 0.61 CH2. C6H5 wherein R stands for a phenyl radical which may be mono-(3) or di-(El/l)substituted by hydroxy, X stands for hydrogen or methyl, with hydrogen in the presence of a nickel catalyst under a pressure'of approximately 40 atmospheres and at a temperature between about 80 C. and about C.

In testimony whereof, we aflix our signa- 5G tures.

FRIEDRICH STOLZ.

KARL BoTToHEn.

JULIUS HALLENSLEBEN.

WALTER KROHS. 80 

